We can cut emissions in half by 2040 if we build smarter cities

To meet the world's climate goals, we must seize the window of opportunity to build climate-smart infrastructure and reduce carbon emissions as cities in the Global South develop, says the Asian Institute of Technology's Shobhakar Dhakal.

Tianjin rising: China aims to raise its city populations from 54.2 per cent in 2012 to 60 per cent in 2020. Cities account for three-quarters of the world's energy-related carbon emissions. Image: Hugi Ólafsson, CC BY-SA 2.0

The problem with infrastructure

Infrastructure contributes to greenhouse gas emissions in two ways: through construction (for example, the energy footprints of cement, steel and aluminium used in the building process) and through the things that go on to use that infrastructure (for example, cars or trains using new roads or tracks).

In a recent study, my colleagues and I have shown that the design of today’s transportation systems, buildings and other infrastructure will largely determine tomorrow’s CO2 emissions.

But by building climate-smart urban infrastructure and buildings, we could cut future emissions in half from 2040 onwards. We could reduce future emissions by ten gigatonnes per year: almost the same quantity currently being emitted by the United States, Europe and India put together (11 gigatonnes).

We assessed cities’ potential to reduce emissions on the basis of three criteria: the emissions savings following upgrades to existing infrastructure; emissions savings from using new, energy-efficient infrastructure; and the additional emissions generated by construction.

In established cities, we found that considerable progress can be made through refurbishment of existing infrastructure. But the highest potential is offered by construction of new, energy-efficient projects from the beginning.

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Perhaps most important is raising the level of ambition in the existing climate policies in cities of all sizes, making them far-reaching, inclusive and robust.

The annual reductions that could be achieved by 2040 by using new infrastructure is three to four times higher than that of upgrading existing roads or buildings.

With this in mind, governments worldwide must guide cities towards low-carbon infrastructure development and green investment.

Besides global megacities such as Shanghai and Mumbai, smaller cities must also be a focus for lowering emissions. Studies have shown a paradox for these places: the capacity for governance and finance are lower in the smaller cities, despite the fact that the majority of future urban populations will grow there, and they will expand quicker than their larger cousins.

We must give up on our obsession with megacities. Without building proper capacity in mid- and small-sized cities to address climate solutions, we cannot meet our climate goals.

Perhaps most important is raising the level of ambition in the existing climate policies in cities of all sizes, making them far-reaching, inclusive and robust. Despite the rhetoric, the scale of real change on ground from existing cities climate actions is unproven and unclear.

But, to further support these good ideas, the world urgently needs support measures for urban mitigation from local to global levels together with a tracking framework and agreed set of indicators for measuring the extent of progress towards low-carbon future.

Only if we start with cities, big and small, will we manage to limit warming to 1.5°C.

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